Impossible bolt? Engine damage if removed? (with pic)

I have a 2003 250EX (same engine as recon 250)

The Recon has a recoil starter, the 250EX does not. The 250EX has a blank plate where the recoil would go. Inside is a bolt that need to be removed for the recoil basket.

The bolt I'm trying remove is connected to the engine, so when ever I try loosen the bolt, the engine will just turn over.

I've tried putting it in 1st gear and reverse gear to lock the engine, but the engine will still spin so the gear has no effect.

Any idea how in heck I would get this bolt off?

Looks like there is a o-ring and another part attached this bolt (#9) (see pic below)

Perhaps I will damage something up by removing the bolt? It might not be as easy as just removing the bolt and re-installing it...? Will it damage the engine or loosen any parts that I can not get access without disassembling the engine? Any idea's?

Thanks